Indexing mechanism



March 22, 1966 J. L. ASH 11 3,241,401

I INDEXING MECHANISM Original Filed Sept. 26, 1963 5 Sheets-Sheet 1 FIG. I

FIG. 2

2 INVENTOI'? l JOHN L. ASH ll QMm ATTORNEY March 22, 1966 A I] INDEXING MECHANISM 5 Sheets-Sheet 2 Original Filed Sept. 26, 1963 March 22, 1966 J. L. ASH u 3,241,401

INDEXING' MECHANISM Original Filed Sept. 26, 1963 5 Sheets-Sheet 5 United States Patent 3,241,401 IN DEXRNG MECHANEM John L. Ash II, Pittsford, N.Y., assignor to The Gleason Works, Rochester, N.Y., a corporation of New York Original application Sept. 26, 1963, Ser. No. 311,712.

Divided and this application .lan. 11, 1965, Ser. No.

6 Claims. (Cl. 74822) .This is a division of application Serial No. 311,712, filed September 26, 1963, and relates to an indexing mechanism for machine tools, especially for gear cutting machines.

An object of the invention is a simple and inexpensive mechanism adapted to effect intermittent indexing or angular advance of a machine tool element, and, after such advance, to hold the element against rotation during a work operation of the machine, for example during the cutting of a gear tooth.

An index mechanism according to the invention comprises a support, a driver mounted for angular oscillation on the support, a driven member rotatable on the support coaxially of the driver, means for oscillating the driver through an angle of at least 360, and a pawl on the support biased for abutment with a shoulder on the driven member to limit each rotational advance of the latter to 360, the driver having a pawl adapted to abut an opposing shoulder on the driven member during each forward stroke of the oscillation and to pass idly thereby during each return stroke, said driver being adapted to move the first-mentioned pawl to a position clear of the first-mentioned shoulder during each return stroke, and cooperating formations on the driver and first-mentioned pawl for holding the latter in said position during the initial part of each forward stroke of the driver.

Apreferred embodiment of the invention is shown in the accompanying drawings, wherein:

, FIG. 1 isa perspective view of the upper portion of a machine tool, in this instance a bevel gear cutting machine;

FIG. 2 is a diagram of the drive for the cradle and the work spindle of the machine;

FIG. 3 is a vertical section through the index mechanism and the means for connecting and disconnecting it from the drive for the work spindle;

FIG. 4 is a plan view, partly in section, of the mechanism shown in FIG. 3;

FIG. 5 is a bottom plan view of the actuating means for the index mechanism, with parts broken away;

FIG. 6 is a plan view of the index mechanism, in plane 6-6 of FIG. 8;

FIG. 7 is a similar plan view but showing the parts in a different position of operation than in FIG. 6; and,

FIG. 8 is a vertical section in the planes designated 8-8 in FIG. 6.

Referring primarily to FIG. 1, the machine comprises a frame 10 supporting a cradle 11 for rotation about horizontal axis 12, the cradle rotatably supporting a tool 13 of the face mill type, whose rotation axis is designated 14. The cutter is adjustable 0n the cradle, both radially of axis 12 and also angularly thereof, the angular adjustment being universal, preferably in the manner disclosed in Patent No. 2,667,818 to A. L. Stewart et al. The work gear G is supported in a suitable work holder on a work spindle 15 journaled for rotation about horizontal axis 16 in a work head 17. A column 18 supports the work head for vertical adjustment thereon, to raise or lower the axis 16 relative to cradle axis 12. The column is adjustable horizontally, in a direction perpendicular to axis 16, on a plate 19 which itself is adjustable in a direct-ion parallel to axis 16 on a swinging base 21. The latter is adjustable upon a sliding base 3,241,401 Patented Mar. 22, 1966 22 about a vertical axis 23 which intersects axis 12. The sliding base is adjustable, and also arranged for infeed and withdrawal on the frame 10, in a direction parallel to axis 12.

Referring to FIG. 2, the drive for the machine includes motor 24, bevel gears 25, cycle speed change gears 26, bevel gears 27 and vertical shaft 28, all supported by the frame 10. The cradle is driven from shaft 28 through bevel gears 29, horizontal shaft 31 and cradle roll cam 32. This cam when rotated oscillates a cam follower lever 33 that is fulcrumed on the frame and pivoted to a connecting rod 34 that is also pivoted, on axis 35, to the cradle 11, with the result that the cradle is rocked back and forth about axis 12 once for each revolution of the cam. Suitable biasing means, not shown, are provided to hold the follower lever against the cam. The pivot axis 35 is adjustable on the cradle around axis 12, whereby the cutter may be placed in the desired position around the latter axis. The work spindle 15 is driven from shaft 28 through bevel gears 36, overhead shaft 37, bevel gears 38 and 39, shaft 40, index change gears 41-44 housed beneath cover 45 on column 18, a telescoping vertical shaft comprising an upper section 46 journaled in the column and a lower section 47 journaled in work head 17, a hypoid pinion 48 on shaft section 47 and a gear 49 on the spindle 15. The lever 33 is of a kind which is adjustable, in a known manner, to vary the angle through which the cradle is rocked back and forth.

For the conventional generation of gears, including mate pinions for nongenerated gears, the bevel gears 38, 39 are brought into mesh and the machine is operated so that the spindle 15 rotates unidirectionally, while the cradle is rocked back and forth about its axis 12. A feed cam 51 on shaft 31 acts to infeed the sliding base 22to advance the work gear G into cutting position at the beginning of each forward roll of the cradle (counterclockwise in FIG. 1) and to withdraw the sliding base to bring the gear clear of the cutter at the end of each forward roll. During the forward roll, the cutter 13, driven either by motor 24 through gearing, not shown, or by a separate motor, generates one tooth slot of the gear. The continuing rotation of the gear G during the idle return roll of the cradle indexes the gear in preparation for the generation of another tooth slot during the next forward roll of the cradle. Throughout the cutting operation a friction brake 52 mounted in the work head 17 acts on the spindle 15 to resist rotation thereof and thereby prevent backlash in the spindle drive gearing. Cam 32 is so shaped that during the cutting phase of operation the cradle and work spindle rotate in substantially constant velocity relation, at a ratio which may be adjusted by exchange of gears 41-44, or by adjustment of the drive ratio of the mechanism connecting cam 32 to the cradle, or both.

Non-generated gears may be cut on the machine by disengaging the gears 38, 39 and driving the spindle gear train 41 to 44 and 46 to 49 by an. intermittent indexing mechanism, designated 53 in FIG. 2. Cutting may be by a method in which the sides of the tooth slots are cut as surfaces of revolution complementary to the surfaces described by the side cutting edges of the rotating cutter 13. In such case the follower lever 33 is disengaged from the cam 32 and the cradle 11 is locked against rotation in the frame. Cutting is effected by infeed of the work-carrying slide 22 by cam 51. The index mechanism 53 is operated intermittently to advance the work spindle by one or more tooth spaces upon each withdrawal of the slide by the cam.

Referring to FIGS. 3 and 6 to 8, the index mechanism 53 comprises a driver 54 reversingly rotatable on bushings 55 on shaft 40 and in part 56 of the column 18. The

driver includes a pawl 57 pivoted thereto by pin 58 and urged clockwise relative thereto by a coil spring 59; and also includes an integral arcuate flange 61. The pawl has a face 62 adapted for abutment with a shoulder 63 on a driven member 64. The latter is mounted on the shaft 40 and has a keyway for receiving a key 65 provided on the shaft. An opposing shoulder 66 on the driven member is adapted for abutment by face 67 of a positioning pawl 68 that is pivoted to the column part 56 by a pin 69 and is urged counterclockwise about the pin by a coil spring 71. Pawl 68 has a pin 72 adapted to engage the flange 61.

A sprocket 73, FIGS. 3 and 5, aiflxed to the lower end of the driver 54, engages an endless chain 74 which extends around. a drive sprocket 75 and a chain-tensioning idler sprocket 76 supported by a pin 77 adjustable on column part 56. Sprocket 75 is co-rotatable in the column part with a pinion 79 which meshes rack teeth on a piston 81. The latter is reciprocable in a cylinder bore 82 in part 56 by hydraulic pressure. A stop button 80 on piston 31 abuts the left cylinder closure 83 to limit counterclockwise rotation of the driver 54, 57, FIGS. 6 and 7, to the broken line position shown in FIG. 7. Clockwise rotation of the driver is limited by abutment of surfaces 62, 63 and 66, 67, as shown in FIG. 6. Thus the angle of rotation of the driver is slightly greater than 360.

The application of hydraulic pressure is controlled by a solenoid-operated reversing valve 04, FIG. 2, which in turn is controlled by a switch 85 actuated by a cam 86 on shaft 31. The hydraulic system further includes a check valve 87 and a pressure-opened or relief valve 88. The valve 84 and a manually-operated valve 89 (see also FIG. 4) control a clamp for holding the spindle 15 against rotation. The clamp comprises a cylinder member 91 supported by the work head 17 and engageable with one face of a flange 92 of the spindle, and a piston 93 in the cylinder engageable with the opposite face of the flange.

Indexing is effected, as soon as cam 51 has withdrawn the sliding base 22 to clear the work from the cutter, by cam 86 closing switch 85; and resetting of the index mechanism follows, after a delay long enough to allow indexing to take place, as a result of re-opening of the switch. The indexing is as follows: During the cutting operation valve 84 connects line 94 to main hydraulic pressure line 95 and. line 96 to main hydraulic exhaust line 97 so that the piston 81 is held in its left limit position in FIGS. 2 and 5, and, valve 09 being open, clamp 9193 is applied by pressure from line 90. The pawl 57 and flange 61 of the driver are in the positions shown in broken lines in FIG. 7. As soon as the switch closes, reversing the valve 84, line 96 is put on pressure and line 94 on exhaust, thereby releasing the clamp. The piston 81 is moved to the right, fluid exhausting from the right cylinder chamber through check valve 87. The driver 54 being rotated clockwise in FIGS. 6 and 7, pawl 57 abuts shoulder 63 and drives member 64 through one complete turn, ending in the position shown in FIG. 6 wherein shoulder 66 abuts the face of pawl 68 under hydraulic pressure. During this rotation, the flange 61 releases the pin 72 of pawl 68 which allows the pawl to move from the position of FIG. 7 to that of FIG. 6.

In the index resetting action, which occurs upon the subsequent reopening of switch 85, valve 84 is reversed to connect line 96 to exhaust line 97 and line 94 to pressure line 95. Pressure is first applied to clamp 91-93, thereby clamping the spindle 15 against rotation, and then, upon opening of valve 08, piston 81 is moved to the left, returning the driver by counterclockwise rotation to bring the pawl 57 and flange 61 to their positions shown in broken lines in FIG. 7. Just prior to the driver reaching the position shown in full lines in FIG. 7 the pawl 57 has, by cam engagement with surface 93 of pawl 68, pivoted the latter pawl to the position shown wherein pin 72 may be engaged and held by flange 61.

When the index mechanism is being used, i.e. when cutting non-generated gears, the shaft 40 is elevated from its position shown in FIG. 3 sufficiently to engage key 65 with the keyway in driver 64 and to separate bevel gear 39 from bevel gear 38. For the purpose of such shifting the gear 39 is rigidly secured to shaft 40 and the latter is journalled for rotation and held against relative axial motion in a flanged quill 99 which is slidable axially in a bore of a change-gearsupporting sector 101, FIGS. 3 and 4, and sector being adjustably secured to the column 18. A U-shaped collar 102 is connected to the sector by screws 103 which also extend through the flange 104 of the quill and are threaded into the sector. When the index mechanism is not to be used and gears 38, 39 are to be meshed, the collar 102 is placed above flange 104, as shown. When the index is to be used, the collar is interposed between flange 104 and sector 101, which elevates the shaft and quill sufficiently to disengage gear 39 from gear 38 and to enter key 65 into the keyway of driver 64. In order that change gear 41 may be at the same elevation in either position of shaft 40, a spacer sleeve 105 of the same thickness as the collar is adapted to be placed either under the gear, as shown, or above the gear. The gear 38 is journaled in a mmeber 106 which is arranged to swivel on the column 18 about the axis of shaft 40 in order to accommodate adjustment of the column on the machine frame, and the sector 101 is also adjustable about this axis in a known manner in order to accommodate change gears of different diameters. A shaft 107 for gears 42 and 43 is rotatably supported by a slide 108 that is adjustable on part 109 of the sector 101 to vary the center distance between shafts 107 and 40.

The valve 89 has an actuating lever 111, FIG. 4, provided with notches 112 and 113 respectively on its lower and upper faces. A flange 114 on collar 102 so interfits with these notches that the collar can be placed in its lower position, beneath flange 104, only when the valve is turned to the broken line position of lever 111, to connect clamp cylinder 91 to line 94, and can be placed in its upper position, shown, only when the valve is turned to the full line position of the lever, to connect the clamp cylinder to exhaust lines 115, 97. The flange 114 of collar 102 and notches 112, 113 of lever 111 thus constitute a mechanical interlock between the valve means controlling the clamp and the shift clutch constituted by quill 99, gears 38, 39, key 65 and the keyway in driver 64, such interlock enabling the clamp to be applied when, and only when, the work spindle is connected for operation by the indexing mechanism 53. When the index mechanism is not to be used in operation of the machine, cam 06 may be removed, which prevents idle actuation of valve 84.

Having now described the preferred embodiment of the invention, and its operation and use, what is claimed is:

1. An index mechanism for a gear machine or other machine tool, comprising a support, a driver mounted for angular oscillation on the support, a driven member rotatable on the support coaxially of the driver, means for oscillating the driver through an angle of at least 360, and a pawl on the support biased for abutment with a shoulder on the driven member to limit each rotational advance of the latter to 360, the driver having a pawl adapted to abut an opposing shoulder on the driven member during each forward stroke of the oscillation and to pass idly thereby during each return stroke, said. driver being adapted to move the first-mentioned pawl to a position clear of the first-mentioned shoulder during each return stroke, and cooperating formations on the driver and first-mentioned pawl for holding the latter in said position during the initial part of each forward stroke of the driver.

2. A mechanism according to claim 1 in which said cooperating formations comprise an arcuate flange on the driver and a projection on the first-mentioned pawl that is engaged by the flange.

3. A mechanism according to claim 1 in which the pawl of the driver has a portion which is engageable with the first-mentioned pawl to move the latter to said position clear of the first-mentioned shoulder.

4. A mechanism according to claim 1 in which there is a clamp means for holding the driven member against rotation in said support, and means for coordinating the operation of said clamp means with that of said means for oscillating the driver, to cause release of the clamp means for each forward. stroke of oscillation of the driver and application of the clamp means prior to each return stroke.

5. A mechanism according to claim 4 including a machine tool spindle connected by gearing to said driven member, said clamp means being applied to said spindle, and there being a brake for said spindle to resist rotation thereof, for eliminating backlash in said gearing during rotational advance of said driven member.

References Cited by the Examiner UNITED STATES PATENTS 2,660,895 12/1953 Waters 74-155 2,947,061 8/1960 Carlsen et al. 74-824 X 2,956,452 10/1960 Dever 74-822 2,972,912 2/1961 Carlsen 74-823 3,166,955 1/1965 Hediger 74822 BROUGHTON G. DURHAM, Primary Examiner. 

1. AN INDEX MECHANISM FOR A GEAR MACHINE OR OTHER MACHINE TOOL, COMPRISING A SUPPORT, A DRIVER MOUNTED FOR ANGULAR OSCILLATION ON THE SUPPORT, A DRIVEN MEMBER ROTABABLE ON THE SUPPORT COAXIALLY OF THE DRIVER, MEANS FOR OSCILLATING THE DRIVER THROUGH ON ANGLE OF AT LEAST 360*, AND A PAWL ON THE SUPPORT BIASED FOR ABUTMENT WITH A SHOULDER ON THE DRIVEN MEMBER TO LIMIT EACH ROTATIONAL ADVANCE OF THE LATTER TO 350*, THE DRIVER HAVING A PAWL ADAPTED TO ABUT AN OPPOSING SHOULDER ON THE DRIVEN MEM- 